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输出: 321</p></blockquote> <h4 id="解法"><a href="#解法" class="header-anchor">#</a> 解法</h4> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">class</span> <span class="token class-name">Solution</span> <span class="token punctuation">{</span>
    <span class="token keyword">public</span> <span class="token keyword">int</span> <span class="token function">reverse</span><span class="token punctuation">(</span><span class="token keyword">int</span> x<span class="token punctuation">)</span> <span class="token punctuation">{</span>
                <span class="token keyword">int</span> flag <span class="token operator">=</span> x <span class="token operator">&gt;</span> <span class="token number">0</span> <span class="token operator">?</span> <span class="token number">1</span> <span class="token operator">:</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span> <span class="token comment">//作为标志位</span>
        <span class="token keyword">int</span> number <span class="token operator">=</span> x <span class="token operator">&gt;</span> <span class="token number">0</span> <span class="token operator">?</span> x <span class="token operator">:</span> <span class="token operator">-</span>x<span class="token punctuation">;</span> <span class="token comment">//只把x当做正整数处理</span>
        <span class="token keyword">int</span> result<span class="token punctuation">;</span>

        <span class="token class-name">String</span> str <span class="token operator">=</span> <span class="token class-name">Integer</span><span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span>number<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">char</span><span class="token punctuation">[</span><span class="token punctuation">]</span> chars <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">toCharArray</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">int</span> n <span class="token operator">=</span> chars<span class="token punctuation">.</span>length<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span>
        <span class="token keyword">int</span> length <span class="token operator">=</span> chars<span class="token punctuation">.</span>length <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">==</span> <span class="token number">0</span> <span class="token operator">?</span> chars<span class="token punctuation">.</span>length<span class="token operator">/</span><span class="token number">2</span> <span class="token operator">:</span> <span class="token punctuation">(</span>chars<span class="token punctuation">.</span>length<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">;</span>
        <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token keyword">char</span> temp <span class="token operator">=</span> chars<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
            chars<span class="token punctuation">[</span>i<span class="token punctuation">]</span> <span class="token operator">=</span> chars<span class="token punctuation">[</span>n<span class="token operator">-</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
            chars<span class="token punctuation">[</span>n<span class="token operator">-</span>i<span class="token punctuation">]</span> <span class="token operator">=</span> temp<span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
        <span class="token class-name">String</span> strReverse <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span>chars<span class="token punctuation">)</span><span class="token punctuation">;</span>
        strReverse <span class="token operator">=</span> strReverse<span class="token punctuation">.</span><span class="token function">trim</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">try</span> <span class="token punctuation">{</span>
            result <span class="token operator">=</span> <span class="token class-name">Integer</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>strReverse<span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">Exception</span> e<span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
        <span class="token keyword">if</span> <span class="token punctuation">(</span>flag <span class="token operator">==</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
            <span class="token keyword">return</span> result <span class="token operator">*</span> flag<span class="token punctuation">;</span>
        <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
            <span class="token keyword">return</span> result <span class="token operator">*</span> flag<span class="token punctuation">;</span>
        <span class="token punctuation">}</span>
    <span class="token punctuation">}</span>

<span class="token punctuation">}</span>
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br></div></div></div> <footer class="page-edit"><!----> <!----></footer> <!---->  <div class="vcomment"><div id="vcomments"></div></div></main></div><div class="global-ui"><!----><!----></div></div>
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